Carbon nanotubes (CNT's) in bulk may comprise high current carrying capacity (˜109 A/cm2) and high thermal conductivity (>3000 W/m−K). Thus, carbon nanotubes are promising materials for use in high current density package interconnects, and package thermal materials, for example. However, the properties of individual nanotubes may be difficult to realized in bulk, due to extremely high thermal and electrical resistances that may be present at interfacial regions.
Nanotube-nanotube or nanotube-metal interface is typically non-ohmic in nature. Electrical conduction across such an interface occurs by quantum mechanical tunneling. Depending upon the nature of the nanotube and/or that of the metal, there is also a Schottky barrier formed at the junction, thereby further increasing the resistance at the interface. Also, phonon scattering may occur at nanotube tips. Thus, the overall thermal and electrical resistance of a given nanotube network or nanotube-based composite may depend strongly upon the interfacial properties.